When you are injured from running and told by a doctor that you have to rest, it's as if you've been told to hand in your wings, surrender your license, turn over your gun and badge, retire your cape and mask, and become normal. Where you were once the least bit special, heroic, or even inspirational, when you are injured and at rest, you are merely ordinary. This is the classic desperate situation that calls for desperate measures; you want to be yourself again--you want to run. But you can't. Is there something else you can do? The sensible answer is yes, if you want to climb into a pool or onto a bike or an elliptical. If you're like me, and not entirely sensible, you want only to run.

After three weeks of rest, the knee I had nearly trashed in a reckless fit of running was on the mend, and I was feeling extremely ordinary. Worse, I was falling extremely out of shape. The familiar creep of fatigue I had worked so hard to lose over 20 months of hitting the road was oozing back in around me. I missed running in ways I never thought I would. I missed the way water tastes after a good sweat. I missed friends I saw only when running. I missed my children's eyes spinning wide when I told them how far I'd run. Running had filled my days with color. Recovery left it dishwater brown.

Each day that passed saw the knee a little better and the rest of the body a little worse. The magical cure seemed to require this: gain weight, lose friends, annoy the family, fall completely out of shape, and soon the joint will heal, but the belly will grow, the stamina will gutter, the triglycerides will soar, the mood will plummet, the clothes won't fit, and man, you'll feel like a regular tiger--a tiger with very sturdy knees in a very tiny cage.

After a full month of inactivity, I began to get used to lying around and found myself at a crossroads. This is the point where a lot of people become the person who used to run but had to stop because it hurt his hip or back or ankle or knee. I didn't want to join that club.

The knee, although not perfect, felt strong enough for a gentle test run. My doctor agreed to allow it only if I stopped the moment I felt the slightest twinge. If I were going to run, I had to do so on a flat surface. But my local road slopes on either side, so it was out. I had an idea, but it wasn't going to be pretty. Some people have no choice but to quit. Others quit because they're not willing to do what they have to do. They shy away from the place where battles are fought--lonely roads through wind-swept deserts, single-track paths over mountain peaks, or in my case, an old treadmill in the basement of my parents' house.

"Hey, you gonna need a towel?!" my dad shouted down the stairs.

"I'm okay," I shouted back, gathering the nerve to mount the treadmill.

"Want me to turn the thing on?"

"I can do it."

"It's a great machine!"

"Yes."

"Welcome to use our shower!"

"Thanks, Dad."

As a rule, I try to avoid any situation that involves a shower in my parents' house, but this was no place for foolish pride. I was underground, it was cold and dark, my mother was making a sandwich for me upstairs. I could only hope she wasn't also cutting off the crusts.

The treadmill stood in the far corner between an unpainted concrete wall and a propane furnace. A small, ground-level window to the right offered a prime view of the central air-conditioning unit. I stepped onto the belt and gazed across the vast expanse of the control panel--a marvel of 1980s technology representing the peak of America's obsession with red indicator lights. I spread my legs to the outer bars and touched the unit to life and it shrieked and ran through a kind of diagnostic check, flashing and blinking a series of hieroglyphic patterns. I plugged a red plastic key into the "ignition" and clipped the attached bungee cord to my shorts. Then I pressed buttons until the belt started moving. Holding the rail, I stepped off the side bars and began to trot.

Zoo animal--that was my first thought. Then: prisoner who has been stripped of outdoor privileges. Then: George Jetson (Jane!! Stop this crazy thing!!). Then a strong and sudden conviction: This is not something I would want anyone to see me doing. I had to run with my chin forward and slightly to the side to keep from falling off the belt. I had to keep my elbows high. I once saw a movie where Brad Pitt wanted to look stupid, so he ran on a treadmill, and it worked very well. But if you already look stupid, what do you look like on a treadmill? You're glad to be alone in a basement, I can tell you that much.

By the first mile, I was thrilled to feel something I hadn't felt in a long time--sweat. The knee was holding steady. I increased the speed and jumped along to keep up with the belt. I hit another button, and with a whine, the front of the unit lifted into my own personal hill. I pressed the down button right away. I hit other buttons to scroll through menu options but knocked my arm against the bungee cord connected to my shorts, and the key popped out, and the whole machine went dead. Fumbling to tether myself back in, I pressed the power button, and the belt kicked back on--reset to zero. I accidentally jerked the key out two more times before quitting.

No longer feeling normal or ordinary, I had a sandwich with Mom while Dad recounted his better runs on the great machine. I'd had a decent workout without a single chirp from the knee, but I knew I wouldn't use it again. I needed the run, but I also needed the wind and the occasional wild animal. I needed the sun and the rain and the waft of air, but more than any of those things, what I needed most of all was the open road.